English wheel
It is a forming machine that works by surface stretching and is related in action to panel beating processes.
Where high-volume production runs of panels are required, the wheel is replaced by a stamping press that has a much higher capital setup cost and longer development time than using an English wheel, but each panel in the production run can be produced in a matter of seconds.
This cost is defrayed across a larger production run, but a stamping press is limited to only one model of panel per set of dies.
On some machines, the operator can turn the top wheel and anvil 90 degrees to the frame to increase the maximum size of the work piece.
The early English machines (as opposed to the American versions), such as Edwards, Kendrick, Brown, Boggs, and Ranalah, etc., had cast iron frames.
Steel tubing, generally of square section, has been used for wheeling machine frames during the past 30 years, in the US particularly, where sheet metal shaping has become a hobby as well as a business.
Shrinking by hand is harder to do and slower than stretching using panel beating tools or wheeling; because of this it should only be used when absolutely necessary.
Aluminium sheet should be annealed before wheeling because rolling at the mill during its production work hardens it.
Strength and rigidity is also provided by the edge treatment such as flanging or wiring, after the fabrication of the correct surface contour has been achieved.
The pressure of the contact area and the number of wheeling passes determine the degree to which the material stretches.
Some operators prefer a foot adjuster so they can maintain constant pressure over varying sheet metal thickness for smoothing, with both hands free to manipulate the work piece.
This type of machine typically has a diagonal lower C-shaped frame that curves lower to the floor, with a hand-operated adjuster close to the anvil wheel holder, instead of the horizontal and long vertical hand adjuster shown in the above picture.
It is a time consuming and fiddly iterative process, that is one of the most difficult and skillful parts of wheeling.
High crown panels/sections may need to be annealed due to work-hardening of the metal, which makes it brittle unworkable and liable to fracture.
Oxy-acetylene welding joints don't have this drawback, provided they are allowed to cool to room temperature in air, but do produce more heat distortion.
It also, more importantly, reduces heat distortion of the surface contour, which must be corrected on the wheel or with hammer and dolly.
An English wheel is a better tool for a skilled craftsman for low-crown applications than manually hammering.
Using a pear shaped mallet and sandbag to stretch the sheet metal (sinking), or by raising on a stake, speeds up the fabrication of higher crown sections.
This is to mount it in a bench vice or a matching female hole in a beak anvil as used by blacksmiths and farriers.)
The English wheel is very effective when used for planishing (for which it was originally patented in England) to a smooth final finish after these processes.
